Revert "Add StreamStartAlgorithm type"

This reverts commit 4047b61899853e97218e5b7b2de3b4a45b1b38c6.

Reason for revert: CFI errors
crbug.com/927659

Original change's description:
> Add StreamStartAlgorithm type
> 
> StartAlgorithms are different from other promise-returning algorithms in
> the streams standard in that they can throw an exception. Add a new
> StreamStartAlgorithm base class to represent them, and a
> CreateStartAlgorithm() function to create ones from JavaScript.
> 
> Design doc:
> https://docs.google.com/document/d/1n0IIRmJb0R-DFc2IhhJfS2-LUwl6iKSBNaR0klr3o40/edit
> 
> BUG=902633
> 
> Change-Id: I0995aa21bbec51ab206a4affc54d861b2c325db4
> Reviewed-on: https://chromium-review.googlesource.com/c/1445342
> Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
> Commit-Queue: Adam Rice <ricea@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#627877}

TBR=ricea@chromium.org,yhirano@chromium.org

Change-Id: I1a9882e1d33236c95ac953a1a1021b9431c4ddca
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 902633
Reviewed-on: https://chromium-review.googlesource.com/c/1449478
Reviewed-by: Keishi Hattori <keishi@chromium.org>
Commit-Queue: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628274}
4 files changed